US470774A - Apparatus for protecting circuits - Google Patents

Description

3 Sheets-Sheet 1.

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WURTS. APPARATUS FOR PROTECTING CIRCUITS.

No. 470,774. Patented Mar. 15, 1892.

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A. WURTS APPARATUS FOR PROTECTING CIRCUITS. No. 470,774. Patented Mar. 15, 1892.

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A. WURTS. APPARATUS FOR PROTECTING CIRCUITS.

No. 470,774. Patented Mar. 15,1892.

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ALEXANDER TVURTS, OF PlT"SBURG, PENNSYLVANIA, ASSIGNOR TO THE \VESTINGHOUSE ELECTRIC AND MANUFACTURING COMPANY, OF SAME PLACE.

APPARATUS FOR PROTECTING CIRCUITS.

SPECIFICATION forming part of Letters Patent No. 470,774, dated March 15, 1892.

Application filed December 16, 1891. fierial No. 415,231- (No model.)

To all whom it may concern:

Be it known that l, ALEXANDER \VURTS, a citizen of the United States, residing in the city of Pittsburg, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvements in Apparatus for Protecting Electric Circuits from Excessive Static Charges, (Case No. 479,) of which the following is a specificai ion.

My invention relates to means for protecting electric generators, motors, and circuits from injuries due to the excessive charges of electricity which they are especially liable to receive during thunderstorms.

I5 Heretofore it has been customary to equip such circuits with means for permitting the discharges of very high potential to pass to the earth across air-spaces or through high resistance mediums, and as the current nor- 2o mally supplied to the circuits is then liable 'to follow across the are or through the circuit thus established it has been necessaryto employ some form of circuit-interrupting device for immediately severing the connections of 2 5 the discharge-circuit or for destroying the are formed by the discharge. Such devices are usually ell'ective in connection with such systems of electrical distribution as do not require an excessive resistance to be introduced 0 between the discharge-points; but in cases where very high electro-motive forces are employed upon the circuits it becomes necessary to separate the discharge-points a considerable distance or to introduce a correspond- 3 5 ingly high resistance in order to prevent the normal currents from striking an arc, and thus short-circuiting the generators. The purpose of my invention is to provide means whereby the circuit may be kept free from excessive 0 static charges and at the same time to prevent the currents generated by the dynamo from flowing through the discharge-circuits.

The general plan of the invention is to provide an earth and discharge circuit for bo -h sides of an electric circuit and to cause the respective sides of the circuit to discharge through such earth-circuit at different times, thereby permitting the static charge to be drawn off from the circuit at rapidly-recurrin g intervals and Without incurring the danger of short-circuiting the machine.

There are many different ways in which the invention may be carried into effect, but the one described, in connection with. the accompanying drawings, will serve to illustrate the method of-operation and a convenientorganization of apparatus therefor.

Figure 1 is a diagram illustrating a general organization of the apparatus and circuits, showing the same as applied to a number of different generators. Fig. 2 is a detailed view of one form of the apparatus.

Referring to the figures, A, A A and A represent electric generators of any suitable character. For convenience I have represented the generators A and A as continuouseurrent machines, and the generators A and A as alternating-current generators, the in vention being applicable to all classes. From the generators A main conductors 1. 2 are 7c led out. These supply work-circuitw. The generator A supplies a work circuit to through conductors 3 A. The class of work to be performed varies in differentinstances. They may be used for operating are or incandescent electric lamps, motors, orany other apparatus. The generator A is represented as supplying a work-circuit 10 comprising in this instance a converter C, the primary coil being connected with the main conductors 5 8o 6, and the secondary coil being connected with the work-circuit. In like manner the generator A supplies one or more converters C through conductors 7 and 8. For the purpose of relieving these conductors from what- 8 5 ever static charge they may acquire, especially during a thunder-storm, means are provided for connecting them at rapidly recurring intervals with a dischargecircuit ll. This circuit has interposed in it lightning- 9o discharge points, consisting of plates h 7L2, having teeth projecting toward each other, as shown, or other suitable form of dischargepoints maybe employed. They are separated from each other bya distance dependent upon 5 the circumstances, being sufficiently near topermit the static charge to escape from any given line to the earth at the moment that line is connected with the discharge-circuit. This may be accomplished by means of some suitable device, such as is illustrated in the figures, which will serve to connect one line at'a time with the discharge-circi iit and to interrupt its connection before the succeeding line is so connected.

In the drawings, Fig. 1, the conductors 1 and 2 are shown as respectively connected by conductors ll and 12 with contact-points Zr. 70 of a suitable circuit-closing device K, and likewise the conductors 3 and eare connected with points 70 M, and the conductors 5 6 7 8 with. points 70 is 10 70 A contact-arm k is caused to make contact with these points in rapid succession in any convenient manner. It may, for instance, be driven by an electric -motor or by a belt from one of the machines. The arm 7c is connected with the dischargeplate It, while the discharge-plate 72.2 is connected with the earth, as indicated at. G. In

the position shown in Fig. 1 the conductor 1 is in connection through the conductor 11 and the point 76' and arm 7:; with the plate h. Any excessive static charge upon this line will then be conducted'to the plate It and across the intervening air-space to the plate 71 and thus escape to the earth,and immediately the arm 70 will pass to the next succeeding plate k and tend to equalize the charge of the line 2 with that of the earth. This operation is repeated'as rapidly as may be necessary to keep all the circuits in a comparatively neutral condition with reference to the earth, thereby relieving them all from any tendency to discharge through the armature of the machine or in any other manner which would be injurious to the apparatus or to the system. It will be noticed that no machine can be short-circuited by this discharge apparatus, since only one terminal of any given machine is connected with the discharge-circuit at the same time. In some instances it may be found preferable to connect two conductors of different machines with the discharging circuit at the same time instead of having them all independent, and if so it may be done without departing from the spirit of my invention. The distance which the points it and h are separate from each other may by these means be made comparatively small, for there will be but little tendency for the current of the machine to pass across the discharge-points, so that the resistance may be much less than would bepe'rmissible if both sides of the circuit were permanently connected with discharge-plates of lightning-arresters. As already stated, where both sides have been connected with the earth it has been necessary to employ some means for interrupting the are formed by a discharge across the points; otherwise the current from the machine will maintain the arc, and thus the machine will be short-circuited. Such interruption of the circuit has been accomplished in various ways; but where currents of very high electro-motive forces are employed considerable difficulty is experienced in accomplishing such interruption.

By my invention the short-circuiting of the machine is avoided by causing the different poles of the machine to be connected with the earth at different times.

In Fig. 2 I have shown more in detail one form of apparatus for connecting the different circuits with the earth in rapid succession.

This device consists of a shaft, which is rotated rapidly in any convenient mannerfor instance, it may be the shaft N ofa dynamo A The shaft N carries the arm 7c, which sweeps over the contact-points k, &c., in the manner already described.

The reason for interposing the dischargeplates 71. h in the discharge-circuit is to provide against the possibility that the conductors of the circuit may not be perfectly insulated from the earth; but in cases where the insulation is perfect or very high these plates may be omitted, as indicated in dotted lines, Fig. 1, and the respective sides of the circuit connected directly with the earth at rapidlyrecnrring intervals, but at different times. It will be understood that the generator cannot be short-circuited by this operation, since only one side is connected with the earth at a time.

I claim as my invention 1. The combination, withone or more electric circuits, of an earth-discharging circuit having an air-space interposed in its length and a contact device connecting the respective sides of the first-named circuit or circuits with said discharge-circuit at different times.

2. The combination, with a dynamo-electric machine and its circuit, of a static-discharge circuit and a circuit-controller alternately connecting the poles'of said machine with said discharge-circuit.

3. The combination, with the circuit of an electric generator, of a rotating-discharge device for discharging the respective conductors of said circuit to the earth, consisting of a series of contacts connected with their respective conductors and a circuit-closing device connecting the respective cont-acts with the earth through a relatively high resistance at different times, substantially as described.

4. The combination, with a dynamo-electric machine and its circuit, of a static-discharge circuit and a circuit-controller discharging the respective sides of the dynamocircuit through said discharge-circuit at different times.

In testimony whereof I have hereunto subscribed my name this llth day of December, A. D. 1891.

ALEXANDER WURTS.

Witnesses:

CHARLES A. TERRY, JAMES W. SMITH.

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